The present invention relates generally to a control system for a chiller unit, and more specifically, to a control system for a steam turbine powered chiller unit that can provide assistance to an operator during a manual startup or shutdown of a steam turbine powered chiller unit.
While most heating, ventilation and air conditioning (HVAC), refrigeration, or chiller systems use electric motors to power the corresponding compressor(s) in the chiller system, some chiller systems can use a steam turbine to power the compressor. Typically, these steam turbine powered chiller systems have required an excessive amount of fieldwork to install and connect the chiller system to the steam turbine system. Some previous steam turbine driven chiller units or systems have involved the packaging of the steam turbine on the chiller unit and resulted in unique installations requiring field routed piping and instrumentation to link the steam turbine system with the chiller unit to complete the installation.
In these previous steam turbine driven chillers systems, many of the controls used with the steam turbine and the chiller unit, e.g., steam turbine governor control, pre-rotation vane control, hot gas control, turbine torque limitation control and surge prevention control, were “stand alone” controls that operated independently of the other controls and did not communicate with the other controls. The use of these separate controls resulted in difficult and complex startup and shutdown procedures, as an operator of the steam turbine driven chiller unit had to monitor all of the separate controls and then initiate the appropriate actions on the appropriate controls at the appropriate times to avoid damaging the steam turbine driven chiller unit or having an unnecessary shutdown of the steam turbine driven chiller unit. In addition, the use of these separate controls results in the requirement that the control operations for the steam turbine system be coordinated with the control operations for the chiller unit for a proper startup or shutdown of the steam turbine chiller unit.
Therefore, what is needed is a control system for a steam turbine powered chiller unit that can assist an operator with a manual startup or shutdown of a steam turbine powered chiller unit and can automatically prevent undesired operational parameters during the manual startup or shutdown of the steam turbine powered chiller unit.